Anthocyanin functions as a natural pigment and also exhibits various physiological activities, such as an antioxidant function, reduction of a cholesterol level, improvement of vision, vascular protection, prevention of arteriosclerosis and heart disease, an anti-ulcer function, an anticancer function, an anti-inflammation function, diabetes suppression, protection from UV radiation, etc. Furthermore, anthocyanin is actively utilized in medicines and is thus receiving attention as a new material for producing health foods and new medicines.
Anthocyanin is unstable in neutral or alkaline solutions, and gradually becomes decolorized when exposed to light even in an acidic solution, and is thus considered to be a structurally unstable material. In particular, factors affecting the stability of an anthocyanin pigment include the chemical structure of anthocyanin, the concentration of the pigment, the pH of the solution, the temperature, the presence or absence of a coexisting pigment, metal ion, enzyme, oxygen, ascorbic acid, sugar, and the like, and the maintenance of chromaticity, that is, the structural stability thereof may vary depending on variation in these factors. Because of this structural instability, many difficulties are encountered in active utilization as foods and medicines, and studies are under way to improve the stability of anthocyanin.
Anthocyanin contained in most food materials is in a monomer form, which is unstable at neutral and alkaline pH and is also weakly resistant to light and heat. The polymer form is present in small amounts in foods but has higher functionality and stability than the monomer, and the typical antioxidant function thereof is also doubled. Recently, research into anthocyanin oligomers that improve subjective symptoms and contrast sensitivity in cases of myopia and amblyopia has been reported.
Related techniques include Korean Patent No. 10-1182630 (Sep. 7, 2012), Korean Patent Application Publication No. 10-2012-0079040 (Jul. 11, 2012), etc.
Aspergillus sp. mold is a useful microorganism for producing enzymes, organic acids and metabolites having pharmacological activity. It has been usefully employed in agriculture as well as in the food industry, the liquor industry, and the pharmaceutical industry, and has been used for producing traditional fermented foods for a long time, and is therefore recognized as a safe strain. Furthermore, since fungi have many exo-enzymes that are secreted to the outside and have a variety of functions, they may be used to economically produce useful materials by means of natural enzymes. There have been conventional reports for the production of anthocyanin oligomers using Aspergillus sp. mold, but the direct use of the strain is problematic in that contamination may occur in the course of production of anthocyanin oligomers.
In order to confirm whether an anthocyanin oligomer may be prepared using an enzyme that is secreted to the outside, without direct use of an Aspergillus sp. strain, the present inventors have devised methods of producing an anthocyanin oligomer using a coenzyme extracted from a culture media of an Aspergillus niger stain and also using as an enzyme glucosidase obtained by analyzing the coenzyme and a multi-enzyme complex containing a wide range of carbohydrases, including arabanase, cellulase, β-glucanase, hemicellulase, and xylanas (commercially available under the trade name Viscozyme® L from Novozymes Corp.), and have ascertained the efficacy thereof, thus culminating in the present invention.